Present type motorcycle rear suspension has the rear wheel vertical travel pivot point located between the engine sprocket and the rear wheel driven sprocket which results in varying drive chain tension as the wheel moves substantially vertically about the pivot point. This variation and drive chain tension causes shock loading of the drive chain in excess of the working load due to the horsepower transmitted to the rear, driven wheel in the form of shock loads which, in some situations, results in premature chain failure due to fatigue or tensile breakage. In modern bikes, the situation which exists for on-road type usage becomes quite severe in off-road usage. Even the average bike ridden a very short distance will cause stretching of the chain as an addition to wear and should be adjusted at least every day. Dirt bikes have very rough treatment due to the dirt soil and need to be adjusted about every thirty minutes.
Accordingly, the ideal situation would be to adjust the chain tension when the bike is to be used for any particular type of travel. However, present day bikes require considerable mechanical adjustments and time consuming effort in order to change the tension of the chain drive. Such a change usually requires removal of certain pieces of equipment, subsequent movement of the rear wheel axle and replacement of the equipment. Under present known conditions, it is not really feasible to be constantly changing the tension that exists on the chain of the bike.
Accordingly, it is an object of the invention to provide a simplified mechanism which varies the distance between the axle of the driven socket and the axle of the drive socket, which in turn adjusts the tension of the chain.
A further object of this invention is to provide means which may be manually operated while the bike is in use which will adjust the tension of the chain.
A further object of this invention is to provide a camming means which will effectively change the distance between the axle of the driven sprocket and the axle of the drive sprocket, such camming means being manually adjustable while the bike is in operation.
A further object of the invention is to provide a means whereby the shock-spring element at the rear of the vehicle may be adjustable in relation to the rider's weight so as to vary the axis of the shock-spring in relation to the axle of the driven wheel. This variation, in turn, causes movement of the axle so as to vary the tension of the spring under changing riding conditions as they occur.
A further object of this invention is to provide the advantage of maintaining alignment during adjustment of the tension as is normally the case when the chain tension must be adjusted under standard practice.